The present invention relates to a fluid dispenser pump, and more particularly to a pump actuated manually to dispense a metered quantity or xe2x80x9cdosexe2x80x9d of fluid each time it is actuated.
Pumps, and in particular xe2x80x9cmetered dosexe2x80x9d pumps that dispense a dose of substance each time they are actuated, are well known from the state of the art. They are generally used to dispense fluids, such as pharmaceuticals, cosmetics, perfumes, or the like. Such a pump generally includes a pump chamber defined between an inlet valve of the pump chamber and an outlet valve of the pump chamber. During actuation, the inlet valve is closed automatically, and after a moment, the outlet valve is opened, thereby making it possible to expel the fluid contained in the pump chamber. To improve the operation of such a pump, it has been proposed to organize the outlet valve of the pump chamber such that, while the pump is being actuated, the pressure of the fluid inside the pump chamber urges the outlet valve towards its closure position, which guarantees full leaktightness. The outlet valve is then opened mechanically, preferably at the end of actuation, once the full dose has been prepared, so as to open the passageway and enable the fluid contained in the pump chamber to be expelled. Such a pump is described in particular in French Patent Application FR 00-13569, filed on Oct. 23, 2000. Although such a pump operates satisfactorily, it can suffer from a problem affecting outlet valve operation. Since the outlet valve is urged towards its closed position by the pressure of the fluid during actuation, and then opened mechanically to enable the fluid to be expelled, there is a risk that the fluid flowing out of the pump chamber after the outlet valve has opened might return said outlet valve to its closed position, so that the dose of fluid might not be dispensed in full. Dose reproducibility is therefore not guaranteed.
An object of the present invention is to provide a fluid dispenser pump that does not suffer from the above-mentioned drawbacks.
An object of the present invention is thus to provide a fluid dispenser pump that guarantees that each dose of fluid is dispensed in full each time the pump is actuated.
A further object of the present invention is to provide a fluid dispenser pump that is simple and inexpensive to manufacture and to assemble.
The present invention thus provides a fluid dispenser pump actuated manually to dispense a metered quantity or xe2x80x9cdosexe2x80x9d of fluid each time it is actuated, said pump including a pump body containing a pump chamber and a return spring resiliently urging the pump towards its rest position and returning it automatically to said rest position after each occasion on which it is actuated, said pump chamber being provided with an outlet valve, said outlet valve being urged towards a closed position by the pressure from the fluid while the pump is being actuated, and being opened mechanically by a valve control element at the end of actuation, once the full dose has been prepared, said pump being characterized in that it includes valve locking means for keeping the outlet valve in the open position while the fluid is being expelled from the pump chamber, to prevent the flow of fluid from closing said outlet valve again before the full dose of fluid has been expelled, said outlet valve being closed mechanically at the end of fluid expulsion by said valve control element under the effect of said return spring of the pump.
Advantageously, the pump chamber is defined between a first piston and a second piston,
Advantageously, said valve locking means consist in wedging the outlet valve in the open position.
Advantageously, said outlet valve comprises a valve element and a valve seat, said valve element comprising a valve head co-operating in leaktight manner with said valve seat when the valve is in the closed position, and a valve body extending axially from said valve head, the diameter of said valve body being smaller than the diameter of said head, said valve body being provided with a valve foot at its end opposite from said valve head, said valve foot being of diameter larger than the diameter of said valve body, the valve control element being mounted to slide around said valve body, and co-operating mechanically with said valve foot to open the outlet valve, and with said valve head to close the outlet valve.
Advantageously, the valve seat is formed in said first piston, said valve head being inserted in said first piston with a friction force, a force greater than said friction force being necessary to move said valve head relative to said valve seat between its closed and open positions.
Advantageously, the valve seat is formed by a radial annular surface that is substantially perpendicular to the central axis of the pump and that surrounds the inlet of an expulsion channel connecting the pump chamber to a dispensing orifice, said valve head co-operating with said radial annular surface via a respective radial surface.
Advantageously, the first piston includes an axial sleeve in which said valve head is mounted to slide, the inside diameter of said axial sleeve being slightly smaller than the outside diameter of said valve head to define said friction force, and therefore to define the force necessary to move said valve head relative to said valve seat.
Advantageously, said axial sleeve is provided with abutment means such as a radial shoulder to define the open position of said valve head.
Advantageously, the surface of said axial sleeve on which said valve head slides is at least partly frustoconical.
Advantageously, said valve head is provided with fluid passageway means such as one or more openings provided in the periphery of said valve head.
The present invention also provides a fluid dispenser including a pump as described above.